Convert CONFIG_SYS_FLASH_EMPTY_INFO to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_FLASH_EMPTY_INFO

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/total_compute_defconfig b/configs/total_compute_defconfig
index 2cb17f5..43db639 100644
--- a/configs/total_compute_defconfig
+++ b/configs/total_compute_defconfig
@@ -53,6 +53,7 @@
 CONFIG_FLASH_CFI_DRIVER=y
 CONFIG_SYS_FLASH_CFI_WIDTH_32BIT=y
 CONFIG_SYS_FLASH_USE_BUFFER_WRITE=y
+CONFIG_SYS_FLASH_EMPTY_INFO=y
 CONFIG_SYS_FLASH_PROTECTION=y
 CONFIG_SYS_FLASH_CFI=y
 CONFIG_LIBAVB=y